The subject matter of the invention is a composition for dyeing hair containing a 4-[4'-[bis-(.beta.-hydroxyethyl)amino]phenylazo]benzenesulfonic acid amide.
Along with oxidative hair dyes formed by the oxidative coupling of one or more developers, direct hair dyes are gaining increasing importance for dyeing hair. Direct hair dyes offer the advantage that they can be applied without the addition of oxidizing agents (for example, hydrogen peroxide) and therefore cause considerably less damage to the hair during the dyeing process.
Good hair dye compositions must satisfy a number of requirements. For example, they must create the desired tint or shade with sufficient intensity and at the same time be absorbed in the hair without excessive discoloration of the scalp. Further, the achieved color must possess sufficient fastness to light, heat, perspiration, hair cleaning agents, and chemicals used for permanent waving. They must also be stable with respect to the action of agents and diluted acids. Finally, these compositions should be unobjectionable in toxicological and dermatological respects.
Since a uniform coloring of the hair from the root to the tip of the hair is generally impossible with dyes from a single class of compounds, combinations of dyes from a number of different classes of compounds are normally used--for example, combinations of amino-, diamino-, or hydroxyamino-nitrobenzene derivatives with azo and anthraquinone dyes.
The most commonly used azo dye is 4'-amino-4-[bis-(.beta.-hydroxyethyl)amino]azobenzene (DISPERSE BLACK 9). It is also known from DE-OS 35 34 885 to use 4'-amino-2-methyl-4-[bis-(.beta.-hydroxyethyl)amino]azobenzene as a hair dye.
Although commonly used in hair dye compositions, the 4'-amino-4-[bis-(.beta.-hydroxyethyl)amino]azobenzene is not completely satisfactory in technical respects relating to application. On the one hand, this compound is suspected of mutagenic behavior. On the other hand, colors produced by this compound and by the hair dyes known from DE-OS 35 34 885 have poor stability relative to acids and acidic preparations such as acidic hair rinses and shampoos, acid permanent wave compositions and fixing agents.